Turbine disk

ABSTRACT

A turbine rotor for a gas turbine engine includes a disk rotationally disposed about a central axis. The disk includes an annular bore portion, an annular rim portion and an annular web portion disposed radially between the bore portion and the rim portion. The annular web portion includes an aft surface. A cylindrical arm is disposed on the aft surface and has a first portion extending axially from the aft surface and a second portion extending radially outward from a distal end of the first portion. The intersection of the first portion and the aft surface defines a fillet, radially inward of the first portion. The fillet is defined by a compound radius.

FIELD

The present disclosure relates to turbine engines and, moreparticularly, to rotors and rotor disks used in turbine engines.

BACKGROUND

Gas turbine engines, such as those utilized in commercial and militaryaircraft, include a compressor that compresses air, a combustor thatmixes the compressed air with a fuel and ignites the mixture, and aturbine that expands the resultant gases from the combustion. Theexpansion of the gases through the turbine drives rotors within theturbine (referred to as turbine rotors) to rotate. The turbine rotorsare connected to a shaft that is connected to rotors within thecompressor (referred to as compressor rotors), thereby driving thecompressor rotors to rotate.

In some gas turbine engines, or sections of some gas turbine engines,the rotors are exposed to significant temperatures. For example, inturbine sections, the resultant gases from the combustion process exposethe turbine disks and, particularly, the rim portions of the turbinedisks, to highly elevated temperatures. Combined with repeatedacceleration and deceleration associated with normal operation, thedisks may experience low cycle fatigue or thermal mechanical fatigue.Discontinuities in disk geometries may exacerbate the onset of suchfatigue.

SUMMARY

In various embodiments, a turbine rotor for a gas turbine engineincludes a disk rotationally disposed about a central axis. The diskincludes an annular bore portion, an annular rim portion and an annularweb portion disposed radially between the bore portion and the rimportion. The annular web portion includes an aft surface. A cylindricalarm is disposed on the aft surface and has a first portion extendingaxially from the aft surface and a second portion extending radiallyoutward from a distal end of the first portion. The intersection of thefirst portion and the aft surface defines a fillet, radially inward ofthe first portion. The fillet is defined by a compound radius, includinga major radius and a minor radius.

In various embodiments, the fillet includes a first smoothing region,which may include a tangential intersection of the major radius and theminor radius. The fillet may also include a second smoothing region,which may include a tangential intersection between the minor radius andan inner radial surface of the cylindrical arm. In various embodiments,the fillet may include a third smoothing region that may include atangential intersection between the major radius and the aft surface ofthe annular web portion.

In various embodiments, the major radius is defined by a major radius ofcurvature and the minor radius is defined by a minor radius ofcurvature. The major radius of curvature generally has a value greaterthan the minor radius of curvature. In various embodiments, the minorradius has a radius of curvature ranging from about 0.200 inches (5.08mm) to about 0.210 inches (5.334 mm). In various embodiments, the majorradius has a radius of curvature ranging from about 4.400 (111.76 mm)inches to about 4.600 (116.84 mm) inches or, more specifically, themajor radius has a radius of curvature ranging from about 4.469 (113.51mm) inches to about 4.531 inches (115.08 mm).

In various embodiments, a turbine rotor for a gas turbine engineincludes a disk rotationally disposed about a central axis. The diskincludes an annular bore portion, an annular rim portion and an annularweb portion disposed radially between the bore portion and the rimportion, the annular web portion has an aft surface. A cylindrical armis disposed on the aft surface and has a first portion extending axiallyoutward from the aft surface. An intersection of the first portion andthe aft surface defines a compound fillet positioned radially inward ofthe first portion, defined by a compound radius having a major radius ofcurvature and a minor radius of curvature.

In various embodiments, the compound fillet further includes a firstsmoothing region, which may include a tangential intersection of themajor radius and the minor radius. In various embodiments, the minorradius has a radius of curvature ranging from about 0.200 inches (5.08mm) to about 0.210 inches (5.334 mm) and the major radius has a radiusof curvature ranging from about 4.469 (113.51 mm) inches to about 4.531inches (115.08 mm).

In various embodiments, the compound fillet may include a major radiusorigin and a minor radius origin. The major radius origin may have aradial value within a radial range from about 0.426 inches (10.82 mm) toabout 0.446 inches (11.32 mm) radially inward of a radially inwardsurface of the first portion of the cylindrical arm and an axial valuewithin an axial range from about 4.469 inches (113.51 mm) to about 4.531inches (115.08 mm) aft of the aft surface. The minor radius origin mayhave a radial value within a radial range from about 0.213 inches (5.41mm) to about 0.223 inches (5.66 mm) radially inward of a radially inwardsurface of the first portion of the cylindrical arm and an axial valuewithin an axial range from about 0.213 inches (5.41 mm) to about 0.223inches (5.66 mm) aft of the aft surface.

In various embodiments, a turbine rotor includes a disk rotationallydisposed about a central axis. The disk includes an annular boreportion, an annular rim portion and an annular web portion. Acylindrical arm is disposed on an aft surface of the annular webportion. The cylindrical arm may have a first portion extending axiallyoutward from the aft surface. An intersection of the first portion andthe aft surface may define a compound fillet radius positioned radiallyinward of the first portion. The compound fillet radius may include aminor radius of curvature having a value ranging from about 0.200 inches(5.08 mm) to about 0.210 inches (5.334 mm) and a major radius ofcurvature having a value ranging from about 4.469 inches (113.51 mm) toabout 4.531 inches (115.08 mm).

In various embodiments, the turbine rotor further includes a majorradius origin and a minor radius origin. The major radius origin mayhave a radial value within a radial range from about 0.426 inches (10.82mm) to about 0.446 inches (11.32 mm) radially inward of a radiallyinward surface of the first portion of the cylindrical arm and an axialvalue within an axial range from about 4.469 inches (113.51 mm) to about4.531 inches (115.08 mm) aft of the aft surface. In various embodiments,the minor radius origin may have a radial value within a radial rangefrom about 0.213 inches (5.41 mm) to about 0.223 inches (5.66 mm)radially inward of a radially inward surface of the first portion of thecylindrical arm and an axial value within an axial range from about0.213 inches (5.41 mm) to about 0.223 inches (5.66 mm) inches aft of theaft surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate various embodiments employing theprinciples described herein and are a part of the specification. Theillustrated embodiments are meant for description and do not limit thescope of the claims.

FIG. 1 is a schematic view of a gas turbine engine, in accordance withvarious embodiments;

FIG. 2 is a schematic view of a turbine assembly, in accordance withvarious embodiments;

FIG. 3 is a schematic view of a rotor and seal assembly, in accordancewith various embodiments;

FIG. 4 is a schematic view of a rim section of a disk, in accordancewith various embodiments;

FIG. 5 is a cross sectional view of a rim and web section of a disk, inaccordance with various embodiments;

FIG. 6 is a cross sectional view of a turbine disk, in accordance withvarious embodiments; and

FIG. 7 is a cross sectional view of a rim and web section of a disk, inaccordance with various embodiments.

DETAILED DESCRIPTION

All ranges may include the upper and lower values, and all ranges andratio limits disclosed herein may be combined. It is to be understoodthat unless specifically stated otherwise, references to “a,” “an,”and/or “the” may include one or more than one and that reference to anitem in the singular may also include the item in the plural.

The detailed description of various embodiments herein makes referenceto the accompanying drawings, which show various embodiments by way ofillustration. While these various embodiments are described insufficient detail to enable those skilled in the art to practice thedisclosure, it should be understood that other embodiments may berealized and that logical, chemical, and mechanical changes may be madewithout departing from the scope of the disclosure. Thus, the detaileddescription herein is presented for purposes of illustration only andnot of limitation. Furthermore, any reference to singular includesplural embodiments, and any reference to more than one component or stepmay include a singular embodiment or step. Also, any reference toattached, fixed, connected, or the like may include permanent,removable, temporary, partial, full, and/or any other possibleattachment option. Additionally, any reference to without contact (orsimilar phrases) may also include reduced contact or minimal contact.

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmenter section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flow path B in abypass duct defined within a nacelle 15, while the compressor section 24drives air along a core or primary flow path C for compression andcommunication into the combustor section 26 and then expansion throughthe turbine section 28. Although depicted as a two-spool turbofan gasturbine engine in the disclosed non-limiting embodiment, it should beunderstood that the concepts described herein are not limited to usewith two-spool turbofans as the teachings may be applied to other typesof turbine engines, including three-spool architectures.

The gas turbine engine 20 generally includes a low speed spool 30 and ahigh speed spool 32 mounted for rotation about an engine centrallongitudinal axis A relative to an engine static structure 36 viaseveral bearing systems 38. It should be understood that various bearingsystems 38 at various locations may alternatively or additionally beprovided and the location of the bearing systems 38 may be varied asappropriate to the application.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a first (or low) pressure compressor 44 and afirst (or low) pressure turbine 46. The inner shaft 40 is connected tothe fan 42 through a speed change mechanism, which in this gas turbineengine 20 is illustrated as a geared architecture 48 to drive the fan 42at a lower speed than the low speed spool 30. The high speed spool 32includes an outer shaft 50 that interconnects a second (or high)pressure compressor 52 and a second (or high) pressure turbine 54. Acombustor 56 is arranged in the gas turbine engine 20 between the highpressure compressor 52 and the high pressure turbine 54. A mid-turbineframe 57 of the engine static structure 36 is arranged generally betweenthe high pressure turbine 54 and the low pressure turbine 46. Themid-turbine frame 57 further supports the bearing systems 36 in theturbine section 28. The inner shaft 40 and the outer shaft 50 areconcentric and rotate via the bearing systems 38 about the enginecentral longitudinal axis A, which is collinear with their longitudinalaxes.

The core airflow is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 thatare in the core airflow path C. The low and high speed turbines 46, 54rotationally drive the respective low speed spool 30 and high speedspool 32 in response to the expansion. It will be appreciated that eachof the positions of the fan section 22, compressor section 24, combustorsection 26, turbine section 28, and fan drive gear system 48 may bevaried. For example, the gear system 46 may be located aft of thecombustor section 26 or even aft of the turbine section 28, and the fansection 22 may be positioned forward or aft of the location of the gearsystem 48.

The engine 20 in one embodiment is a high-bypass geared aircraft engine.In a further embodiment, the engine 20 bypass ratio is greater thanabout six (6), with one embodiment being greater than about ten (10),the geared architecture 48 is an epicyclic gear train, such as aplanetary gear system or other gear system, with a gear reduction ratioof greater than about 2.3 and the low pressure turbine 46 has a pressureratio that is greater than about five. In one disclosed embodiment, theengine 20 bypass ratio is greater than about ten (10:1), the fandiameter is significantly larger than that of the low pressurecompressor 44, and the low pressure turbine 46 has a pressure ratio thatis greater than about five 5:1. A low pressure turbine 46 pressure ratiois the pressure measured prior to inlet of the low pressure turbine 46as related to the pressure at the outlet of the low pressure turbine 46prior to an exhaust nozzle. It should be understood, however, that theabove parameters are descriptive of only one embodiment of a gearedarchitecture engine and that the present invention is applicable toother gas turbine engines, including direct drive turbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition typically cruise at about 0.8 Mach andabout 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft(10,668 meters), with the engine at its best fuel consumption—also knownas “bucket cruise Thrust Specific Fuel Consumption (‘TSFC’)”—is theindustry standard parameter of lbm of fuel being burned divided by lbfof thrust the engine produces at that minimum point. “Low fan pressureratio” is the pressure ratio across the fan blade alone, without a FanExit Guide Vane (“FEGV”) system. The low fan pressure ratio as disclosedherein according to one non-limiting embodiment is less than about 1.45.“Low corrected fan tip speed” is the actual fan tip speed in ft/secdivided by an industry standard temperature correction of [(Tram°R)/(518.7°R)]̂0.5. The “Low corrected fan tip speed” as disclosed hereinaccording to one non-limiting embodiment is less than about 1150ft/second (350.5 meters/second).

With continued reference to FIG. 1, and with like numerals indicatinglike elements, FIG. 2 illustrates schematically a turbine section, suchas a high pressure turbine assembly 54, while FIG. 3 illustratesschematically a close up view of a rotor and seal assembly 68. The highpressure turbine assembly 54 includes a first rotor 34 and a secondrotor 35, with the second rotor 35 disposed aft (or downstream) of thefirst rotor 34. The second rotor 35 generally includes a bore (see,e.g., 304 at FIG. 6), a web 70 radially outward of the bore and a rim 72radially outward of the web 70. The bore, web 70 and rim 72 extendcircumferentially about the engine central longitudinal axis A andcollectively comprise a rotor disk or turbine disk 37. The second rotor35 includes an aft surface 62 and a forward surface 64. The second rotor35 further includes a plurality of blades 66 spaced circumferentiallyabout and connected to the rim 72. In various embodiments, the blades 66are connected to the rim 72 using attachment sections (not shown)disposed at the base of the blades that are received within bladeretention slots (see, e.g., 136 at FIG. 4) positioned within the rim 72.The attachment sections (or blade roots) and the blade retention slotscan have various contours, including, for example, dove-tail, fir-treeor bulb type contours. In other embodiments, the blades 66 are formedintegrally with the rim 72. While the above description has focused onthe second rotor 35, the same general characteristics apply to the firstrotor 34.

Referring still to FIGS. 2 and 3, the rotor and seal assembly 68includes an annular platform 80 that extends circumferentially about theengine central longitudinal axis A. The annular platform 80 includes abase 82 that interfaces with an outer portion 73 of the rim 72. The base82 houses a seal 84 that prevents hot gases flowing in the core airflowpath C from leaking into the disk region of the rotor 35. The annularplatform further includes an arm 86 and hook 88. In various embodiments,the arm 86 extends generally in a radial direction while the hook 88extends generally in the axial direction. The hook 88 includes an uppersurface 90 that is sized and configured to slidably engage a tab portion92 of the rim 72. The tab portion 92 includes a lower surface 94 thatmatches the upper surface 90 of the hook 88. As described in thesections that follow, the tab portion 92 may, in various embodiments,comprise a plurality of tabs interspersed with or separated by aplurality of slots, both the tabs and slots extending circumferentiallyabout the rim 72 of the disk 37 or rotor 35. Still referring to FIG. 3,the rotor and seal assembly 68 further includes a second annularplatform 96 disposed aft of the rim 72. The second annular platform 96includes a base 97 that interfaces with an outer portion 93 of the rim72. The base 97 houses a seal 98 that prevents hot gases flowing in thecore airflow path C from leaking into the disk region of the rotor 35.

Referring now to FIG. 4, a portion of a rotor disk 200 is illustrated,exhibiting various features of the present disclosure. The rotor disk200 includes a web portion 202 and rim portion 203. The rim portion 203includes a plurality of radially extending blade posts 208 that eachincludes one or more circumferentially extending branch elements 230.The branch elements 230 positioned on adjacent blade posts 208 are sizedand configured to secure corresponding attachment sections of individualrotor blades. Each blade post 208 generally includes a tip 222, a base224 a forward facing surface 240 and an aft facing surface 242. Invarious embodiments of the present disclosure, the forward facingsurface 240 may have a first portion 250 that extends radially inwardfrom the tip 222 to a blade post transition portion 216, positioned in aregion between the tip 222 and the base 224. In various embodiments, theblade post transition portion 216 may be positioned or disposed at alocation between about 25% and 50% of the length between the tip 222 andthe base 224 in a radially outward direction from the base 224. Invarious embodiments, the blade post transition portion 216 may bepositioned or disposed proximate a radially-most inward one of thebranch elements 230. The forward facing surface 240 may further includea slope portion 218 that extends radially inward from the bladetransition portion 216 toward the base 224. In various embodiments, theslope portion 218 also extends axially in the forward direction, thusproviding a slope or a face with a surface normal that resides at anon-zero angle with respect to an axial direction 226 of the rotor disk200.

Still referring to FIG. 4, a plurality of tabs 210 is spacedcircumferentially about the rim portion 203. A slot 214 is positionedbetween adjacent pairs of tabs 210, providing a plurality of slots 214circumferentially spaced about the rim portion 203. In variousembodiments, a tab 210 is positioned, generally, radially inward ofevery other (e.g., odd numbered, counting circumferentially) blade post208. Similarly, a slot 214 is positioned, generally, radially inward ofthe remaining (e.g., even numbered) blade posts 208. Positioning thetabs 210 with respect to the blade posts 208 in such manner provides an“in-phase” relation between the positioning of the tabs 210 (and theslots 214) and the blade posts 208. The “in-phase” relation contrastswith embodiments where there is no clear phase relation between thecircumferential positioning of tabs with respect to the circumferentialpositioning of the blade posts—e.g., embodiments where some tabs arepositioned radially inward of blade posts while other tabs arepositioned radially inward of troughs between adjacent blade posts whilestill other tabs are positioned radially inward of a portion of a troughand a portion of a blade post adjacent the through. Thus, in variousembodiments of the present disclosure, the number of tabs (N_(Tabs))will equal the number of slots (N_(Slots)), while both N_(Tabs) andN_(Slots) will equal one-half the number of posts (N_(Posts)). Invarious embodiments, N_(Tabs)=N_(Slots)=41 and N_(Posts)=82. In variousembodiments, each tab 210 may have a circumferential length 252 and eachslot 214 may have a circumferential length 254. In addition, in variousembodiments, the circumferential length 252 of each tab 210 may be aboutthe same as the circumferential length 254 of each slot 214. In variousembodiments, the circumferential length 252 of each tab 210 may begreater than or less than the circumferential length 254 of each slot214. In various embodiments, the circumferential length 254 of each slot214 has a value within a range from about 0.900 inches (22.86 mm) toabout 0.950 inches (24.13 mm). In various embodiments, thecircumferential length 254 of each slot 214 has a value within a rangefrom about 0.910 inches (23.11 mm) to about 0.930 inches (23.62 mm) andN_(Tabs)=N_(Slots)=41.

Referring now to FIGS. 4 and 5, various geometries for the tabs 210,slots 214 and forward facing surfaces 240 with respect to the rimportion 203 are described. As stated above, the forward facing surface240 of each blade post 208 includes a first portion 250 that extendsradially inward from the tip 222 to a blade post transition portion 216,positioned in a region between the tip 222 and the base 224. The forwardfacing surface 240 may further include a slope portion 218 that extendsradially inward from the blade transition portion 216 toward the base224. In various embodiments, the slope portion 218 may extend beyond thebase 224 to intersect with a face portion 220 of a tab 210. Intersectionof the slope portion 218 with a face portion 220 typically occurs wherea tab 210 is disposed radially inward of a post 208, as illustrated inFIG. 4. In various embodiments, the face portion 220 of each tab 210extends radially inward at an angle of about 85 degrees to about 95degrees with respect to the longitudinal axis of the rotor disk 200 orthe engine central longitudinal axis A. In various embodiments, the faceportion 220 extends radially inward at an angle of about 90 degrees withrespect to the longitudinal axis of the rotor disk 200. In other words,at an angle of 90 degrees, the face portion 220 defines a surface thatis normal (i.e., perpendicular) to the central longitudinal axis A.

Still referring to FIGS. 4 and 5, the forward facing surface 240 of eachblade post 208, including the first portion 250, the blade transitionportion 216 and the slope portion 218 defines an axial profile. Forblade posts 208 having a tab 210 positioned radially inward of the base224, the axial profile will include the face portion 220 of the tab 210.For blade posts 208 having a slot 214 positioned radially inward of thebase, the axial profile will terminate at the radially outermost part ofthe slot. The axial profile may include sub-profiles. For example, theaxial profile may include a first axial profile extending from the bladetransition portion 216 to the face portion 220 of a tab 210 andincluding the slope portion 218. Generally, the blade posts arepositioned in a first radially outermost rim portion 204 while the tabs210 and slots are positioned in a second radially outermost rim portion206. The second radially outermost rim portion 206 resides radiallyinward of the first radially outermost rim portion 204.

In various embodiments, the blade transition portion 216, the slopeportion 218 and the face portion 220 may be defined through specifiedgeometrical values. For example, referring primarily to FIG. 5, theblade transition portion 216 may include a radius of curvature 260. Invarious embodiments, the radius of curvature 260 may have values rangingfrom about 0.100 inches (2.54 mm) to about 0.300 inches (7.62 mm). Invarious embodiments, the radius of curvature may range from about 0.194inches (4.92 mm) to about 0.214 inches (5.43 mm). In variousembodiments, the radius of curvature 260 may be specified to have avalue of about 0.204 inches (5.18 mm). Similarly, the slope portion 218may be defined by a slope angle 262. In various embodiments, the slopeangle 262 may have a value of about 60 degrees to about 65 degrees, withthe angle defined as extending radially inward from an axial direction.In various embodiments, the slope angle 262 may range from about 61.5degrees to about 62.5 degrees. In various embodiments, the slope angle262 may be specified to be about 62 degrees. The geometry of the slots214 may also be defined by geometrical values. For example, each slot214 may include a roof portion 231 that is defined by a roof angle 264.In various embodiments, the roof angle 264 may range from about 35degrees to about 45 degrees, with the angle defined as extendingradially outward from an axial direction. In various embodiments, theroof angle 264 may range from about 39.5 degrees to about 40.5 degrees.In various embodiments, the roof angle 264 may be specified to be about40 degrees. In various embodiments, a radial length 272 between theblade transition portion 216 and a radially outermost point 274 of theface portion 220 of each tab 210 has a value within a range of about0.590 inches (14.98 mm) to about 0.600 inches (15.24 mm). In variousembodiments, an axial length 275 between the first portion 250 of theblade posts 208 and the face portion 220 of the tabs 210 has a valuewithin a range of about 0.290 inches (7.36 mm) and about 0.300 inches(7.62 mm).

Referring now to FIG. 6, a cross sectional view of a turbine disk 300,in accordance with various embodiments is illustrated. The turbine disk300 includes a rim portion 302 and a bore portion 304. A web portion 306is disposed radially between the rim portion 302 and the bore portion306. In various embodiments, each of the rim portion 302, the boreportion 304 and the web portion 306 is annular about a central axis 308.The web portion 306 may include a fore surface 310 and an aft surface312. The turbine disk 300 may further include a cylindrical arm 314disposed on and intersecting the aft surface 312. The cylindrical arm314 may include a first portion 316 that extends generally in an axialdirection from the aft surface 312. A second portion 318 of thecylindrical arm 314 extends radially outward from a distal end 317 ofthe first portion 316. In various embodiments, the cylindrical arm 314may be axisymmetric about the central axis 308. In various embodiments,the cylindrical arm 314 may comprise a plurality of segments spacedcircumferentially about the central axis 308, with spaces or slotspositioned between adjacent segments. The intersection of thecylindrical arm 314 with the aft surface 312 of the web portion 306 maydefine a fillet 320 radially inward of the first portion 316 of thecylindrical arm 314.

In various embodiments, the fillet 320 may comprise a compound fillet322. For example, with continued reference to FIG. 6, and with likenumerals indicating like elements, FIG. 7 provides a cross sectionalclose-up view of a compound fillet 322, in accordance with variousembodiments, near the rim portion 302 of the turbine disk 300. Invarious embodiments, the compound fillet 322 may be defined by acompound radius, which may include a minor radius 324 and a major radius326. In various embodiments, the minor radius 324 is defined by a minorradius of curvature having a range from about 0.190 inches (4.82 mm) toabout 0.220 inches (5.58 mm) and the major radius 326 is defined by amajor radius of curvature having a range from about 4.400 inches (111.76mm) to about 4.600 inches (116.84 mm). In various embodiments, the minorradius 324 is defined by a minor radius of curvature having a range fromabout 0.200 inches (5.08 mm) to about 0.210 inches (5.334 mm) and themajor radius 326 is defined by a major radius of curvature having arange from about 4.469 inches (113.51 mm) to about 4.531 inches (115.08mm).

In various embodiments, an axial value 340 of the origin of the minorradius 324 is positioned within an axial range from about 0.200 inches(5.08 mm) to about 0.240 inches (6.09 mm) aft of the aft surface 312. Invarious embodiments, a radial value 342 of the origin of the minorradius is also positioned within a radial range from about 0.200 inches(5.08 mm) to about 0.240 inches (6.09 mm) radially inward of a radiallyinward surface 344 of the first portion 316 of the cylindrical arm 314.In various embodiments, the axial value 340 of the origin of the minorradius 324 is positioned within an axial range from about 0.213 inches(5.41 mm) to about 0.223 inches (5.66 mm) aft of the aft surface 312. Invarious embodiments, the radial value 342 of the origin of the minorradius is also positioned within a radial range from about 0.213 inches(5.41 mm) to about 0.223 inches (5.66 mm) radially inward of theradially inward surface 344 of the first portion 316 of the cylindricalarm 314.

In various embodiments, an axial value 346 of the origin of the majorradius 326 is positioned within an axial range from about 4.400 inches(111.76 mm) to about 4.600 inches (116.84 mm) aft of the aft surface312. In various embodiments, a radial value 348 of the origin of themajor radius is also positioned within a radial range from about 0.400inches (10.16 mm) to about 0.480 inches (12.18 mm) radially inward ofthe radially inward surface 344 of the first portion 316 of thecylindrical arm 314. In various embodiments, the axial value 346 of theorigin of the major radius 326 is positioned within an axial range fromabout 4.469 inches (113.51 mm) to about 4.531 inches (115.08 mm) aft ofthe aft surface 312. In various embodiments, the radial value 348 of theorigin of the major radius is also positioned within a radial range fromabout 0.426 inches (10.82 mm) to about 0.446 inches (11.32 mm) radiallyinward of the radially inward surface 344 of the first portion 316 ofthe cylindrical arm 314. In various embodiments, the radial value 348 ofthe origin of the major radius 326 has a value equal to the radial value342 of the origin of the minor radius 324.

In various embodiments, the minor radius 324 intersects tangentiallywith the radially inward surface 344 of the first portion 316 of thecylindrical arm 314, thereby defining a first point of tangency 330. Invarious embodiments, the major radius 326 intersects tangentially withthe aft surface 312, thereby defining a second point of tangency 332. Invarious embodiments, the minor radius 324 and the major radius 326intersect tangentially with each other, thereby defining a third pointof tangency 334. In various embodiments, the third point of tangency 334defines a tangent plane that is tangent with the aft surface 312. Invarious embodiments, the minor radius 324 and the major radius 326 mayintersect non-tangentially with one another. In various embodiments,smoothing of the non-tangential intersection may occur in a smoothingregion 350 to remove sharp or discontinuous interfaces. Smoothingregions may also occur at the intersection of the minor radius 324 andthe radially inward surface 344 of the first portion 316 of thecylindrical arm 314 and at the intersection of the major radius 326 andthe aft surface 312 radially inward of the first portion 316 of thecylindrical arm 314.

Referring still to FIG. 6, the bore 304 is illustrated having a foresurface 360 and an aft surface 362. The aft surface 362 of the bore 304includes an aft web transition portion 364, an aft ramp portion 366 andan aft base transition portion 368. Likewise, the fore surface 360includes a fore web transition portion 370, a fore ramp portion 372 anda fore base transition portion 374. In various embodiments, the aft webtransition portion 364 and the fore web transition portion arepositioned at a radial length equal to about 14 inches (355.6 mm) toabout 15 inches (381 mm) from an axial center line or central axis 308.In various embodiments, either or both of the aft ramp portion 366 andthe fore ramp portion 372 have substantially linear profiles, meaningthe profiles have curvature radii greater than about 5 inches (127 mm).In various embodiments, the curvature radii may have values equal toabout 2 inches (50.8 mm) and in various embodiments the curvature radiimay range from about 2 inches (50.8 mm) to about 5 inches (127 mm). Invarious embodiments, either or both of the aft ramp portion 366 and thefore ramp portion 372 include linear segments between their respectiveweb and base transition portions. In various embodiments, the linearsegments may span the entire ramp portions. The aft base transitionportion 368 may include a face portion 376 that defines a surface normalpointing in a direction substantially parallel with the central axis308—e.g., within a range of angles from about 0 degrees (parallel) toabout 20 degrees, pointing radially outward from the central axis 308.In various embodiments, the face portion 376 defines a surface normalpointing in a direction parallel with the central axis 308.

In various embodiments, the aft web transition portion 364 may bedefined by a first radius of curvature that smoothly connects the aftsurface 312 of the web portion 306 and the aft ramp portion 366.Likewise, the fore web transition portion 370 may be defined by a secondradius of curvature that smoothly connects the fore surface 310 of theweb portion 306 and the fore ramp portion 372. In various embodiments,the first radius of curvature and the second radius of curvature areequal in value. The first and second radii of curvature may have valuesequal to about 2 inches (50.8 mm) in various embodiments, between about2 inches (50.8 mm) and about 5 inches (127 mm) in various embodimentsand greater than 5 inches (127 mm) in various embodiments.

In various embodiments, the web portion 306 further includes a baseportion 307. The base portion 307 may include a spool engagement surface380 and may further include a first arm 382 extending in the aftdirection and a second arm 384 extending in the fore direction. Invarious embodiments, the spool engagement surface 380 has a length 394within a range from about 3.6 (91.44 mm) inches to about 3.7 inches(93.98 mm). The base portion 307 may further include a radiallyextending first transition portion 386 connecting an aft end of thespool engagement surface 380 to a radially inward portion of the firstarm 382 and a radially extending second transition portion 388connecting a fore end of the spool engagement surface 380 to a radiallyinward portion of the second arm 384. The radially extending firsttransition portion 386 may include a first face portion 390 that definesa surface normal pointing in a direction substantially parallel with thecentral axis 308—e.g., within a range of angles from about 0 degrees(parallel) to about 20 degrees, pointing radially outward from thecentral axis 308. In various embodiments, the first face portion 390defines a surface normal pointing in a direction parallel with thecentral axis 308. Similarly, the radially extending second transitionportion 388 may include a second face portion 392 that defines a surfacenormal pointing in a direction substantially parallel with the centralaxis 308—e.g., within a range of angles from about 0 degrees (parallel)to about 20 degrees, pointing radially outward from the central axis308, but in a direction opposite that of the first face portion 390. Invarious embodiments, the second face portion 392 defines a surfacenormal pointing in a direction parallel with the central axis 308,though opposite that of the first face portion 390.

Various embodiments of the present disclosure are believed to provideimproved distributions of stress—e.g., axial, radial and hoop—throughoutthe turbine disk while tending to minimize local increases in weight toreduce maximum stress values occurring at discontinuities and regions ofhigh curvature. For example, adding weight to the rim portion near thetabs allows a reduction in maximum stress values through a reduction indiscontinuities and regions of high curvature. Similarly, adding weightto the bore region through use of substantially linear ramp portions orthe incorporation of base transition portions as described above providereductions in maximum stress values.

With reference to the foregoing illustrations, description andembodiments, the turbine rotors or turbine disks are described asdevices for utilization in a turbine section of a gas turbine engine.One of skill in the art, having the benefit of this disclosure, willunderstand that the disclosed rotors or disks can be utilized in otherstages or sections of a gas turbine engine. Furthermore, while describedabove within the context of a geared turbofan engine, one of skill inthe art will understand the above described rotor or disk can bebeneficially utilized in other turbine applications including, but notlimited to, direct drive turbine engines, land based turbines, andmarine turbines.

Finally, it is further understood that any of the above describedconcepts can be used alone or in combination with any or all of theother above described concepts. Although various embodiments have beendisclosed and described, one of ordinary skill in this art wouldrecognize that certain modifications would come within the scope of thisdisclosure. Accordingly, the description is not intended to beexhaustive or to limit the principles described or illustrated herein toany precise form. Many modifications and variations are possible inlight of the above teaching.

Benefits, other advantages, and solutions to problems have beendescribed herein with regard to specific embodiments. Furthermore, theconnecting lines shown in the various figures contained herein areintended to represent exemplary functional relationships and/or physicalcouplings between the various elements. It should be noted that manyalternative or additional functional relationships or physicalconnections may be present in a practical system. However, the benefits,advantages, solutions to problems, and any elements that may cause anybenefit, advantage, or solution to occur or become more pronounced arenot to be construed as critical, required, or essential features orelements of the disclosure. The scope of the disclosure is accordinglyto be limited by nothing other than the appended claims, in whichreference to an element in the singular is not intended to mean “one andonly one” unless explicitly so stated, but rather “one or more.”Moreover, where a phrase similar to “at least one of A, B, or C” is usedin the claims, it is intended that the phrase be interpreted to meanthat A alone may be present in an embodiment, B alone may be present inan embodiment, C alone may be present in an embodiment, or that anycombination of the elements A, B and C may be present in a singleembodiment; for example, A and B, A and C, B and C, or A and B and C.Different cross-hatching is used throughout the figures to denotedifferent parts but not necessarily to denote the same or differentmaterials.

Systems, methods and apparatus are provided herein. In the detaileddescription herein, references to “one embodiment”, “an embodiment”,“various embodiments”, etc., indicate that the embodiment described mayinclude a particular feature, structure, or characteristic, but everyembodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Further, when a particular feature,structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed. After reading the description, it will be apparent to oneskilled in the relevant art(s) how to implement the disclosure inalternative embodiments.

Furthermore, no element, component, or method step in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element, component, or method step is explicitly recited inthe claims. No claim element herein is to be construed under theprovisions of 35 U.S.C. 112(f) unless the element is expressly recitedusing the phrase “means for.” As used herein, the terms “comprises”,“comprising”, or any other variation thereof, are intended to cover anon-exclusive inclusion, such that a process, method, article, orapparatus that comprises a list of elements does not include only thoseelements but may include other elements not expressly listed or inherentto such process, method, article, or apparatus.

What is claimed:
 1. A turbine rotor, comprising: a disk rotationallydisposed about a central axis, the disk including an annular boreportion; an annular rim portion; an annular web portion disposedradially between the bore portion and the rim portion, the annular webportion having an aft surface; and a cylindrical arm disposed on the aftsurface, the cylindrical arm having a first portion extending axiallyfrom the aft surface and a second portion extending radially outwardfrom a distal end of the first portion, the intersection of the firstportion and the aft surface defining a fillet, radially inward of thefirst portion, wherein the fillet is defined by a compound radius. 2.The turbine rotor of claim 1, wherein the compound radius includes amajor radius and a minor radius.
 3. The turbine rotor of claim 2,wherein the fillet further includes a first smoothing region.
 4. Theturbine rotor of claim 3, wherein the first smoothing region includes atangential intersection of the major radius and the minor radius.
 5. Theturbine rotor of claim 4, wherein the fillet further includes a secondsmoothing region.
 6. The turbine rotor of claim 5, wherein the secondsmoothing region includes a tangential intersection between the minorradius and an inner radial surface of the cylindrical arm.
 7. Theturbine rotor of claim 6, wherein the fillet further includes a thirdsmoothing region that includes a tangential intersection between themajor radius and the aft surface of the annular web portion.
 8. Theturbine rotor of claim 7, wherein: the major radius is defined by amajor radius of curvature; and the minor radius is defined by a minorradius of curvature.
 9. The turbine rotor of claim 8, wherein the majorradius of curvature has a value greater than the minor radius ofcurvature.
 10. The turbine rotor of claim 2, wherein the minor radiushas a radius of curvature ranging from about 0.200 inches to about 0.210inches.
 11. The turbine rotor of claim 10, wherein the major radius hasa radius of curvature ranging from about 4.400 inches to about 4.600inches.
 12. The turbine rotor of claim 11, wherein the major radius hasa radius of curvature ranging from about 4.469 inches to about 4.531inches.
 13. A turbine rotor, comprising: a disk rotationally disposedabout a central axis, the disk including an annular bore portion; anannular rim portion; and an annular web portion disposed radiallybetween the bore portion and the rim portion, the annular web portionhaving an aft surface; and a cylindrical arm disposed on the aftsurface, the cylindrical arm having a first portion extending axiallyoutward from the aft surface, wherein an intersection of the firstportion and the aft surface defines a compound fillet positionedradially inward of the first portion, and wherein the compound fillet isdefined by a compound radius having a major radius of curvature and aminor radius of curvature.
 14. The turbine rotor of claim 13, whereinthe fillet further includes a first smoothing region.
 15. The turbinerotor of claim 14, wherein the first smoothing region includes atangential intersection of the major radius and the minor radius. 16.The turbine rotor of claim 15, wherein the minor radius has a radius ofcurvature ranging from about 0.200 inches to about 0.210 inches.
 17. Theturbine rotor of claim 16, wherein the major radius has a radius ofcurvature ranging from about 4.469 inches to about 4.531 inches.
 18. Theturbine rotor of claim 17, further comprising a major radius origin anda minor radius origin, wherein the major radius origin has a radialvalue within a radial range from about 0.426 inches to about 0.446inches radially inward of a radially inward surface of the first portionof the cylindrical arm and an axial value within an axial range fromabout 4.469 inches to about 4.531 inches aft of the aft surface andwherein the minor radius origin has a radial value within a radial rangefrom about 0.213 inches to about 0.223 inches radially inward of aradially inward surface of the first portion of the cylindrical arm andan axial value within an axial range from about 0.213 inches to about0.223 inches aft of the aft surface.
 19. A turbine rotor, comprising: adisk rotationally disposed about a central axis, the disk including anannular bore portion; an annular rim portion; an annular web portion;and a cylindrical arm disposed on an aft surface of the annular webportion, the cylindrical arm having a first portion extending axiallyoutward from the aft surface, wherein an intersection of the firstportion and the aft surface defines a compound fillet radius positionedradially inward of the first portion, and wherein the compound filletradius includes a minor radius of curvature having a value ranging fromabout 0.200 inches to about 0.210 inches and a major radius of curvaturehaving a value ranging from about 4.469 inches to about 4.531 inches.20. The turbine rotor of claim 19, further comprising a major radiusorigin and a minor radius origin, wherein the major radius origin has aradial value within a radial range from about 0.426 inches to about0.446 inches radially inward of a radially inward surface of the firstportion of the cylindrical arm and an axial value within an axial rangefrom about 4.469 inches to about 4.531 inches aft of the aft surface andwherein the minor radius origin has a radial value within a radial rangefrom about 0.213 inches to about 0.223 inches radially inward of aradially inward surface of the first portion of the cylindrical arm andan axial value within an axial range from about 0.213 inches to about0.223 inches aft of the aft surface.